Re: Pressure \"spikes\" on Big Magnum Cartridges....
The barrel heating up will warm the ammo enough to do this, I've saw the same thing in my 7mm AM, leaving the third round in the chamber an extra 2 min. will boost my MV over 200 fps. but I shoot WC872 and its pretty heat sensative, on an 80 degree sunny day, a typical 3 shot string goes like this first shot is fine, light bolt lift, effortless extraction, shot #2, slightly heavy lift, slightly sticky extraction, mildly cratered primer, third shot, !@$%*& heavy bolt lift, and very sticky, primer may or may not pierce. 60 degrees and below there isn't a problem.
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